French Drain Installation in Kansas City

A french drain is a trench with a perforated pipe in the bottom, wrapped in filter fabric and backfilled with washed rock. Water in the surrounding soil moves into the rock, falls into the pipe and leaves by gravity. That is the whole mechanism.

Two things decide whether it works: where the water actually is, and where it can go.

It is not a cure for every wet basement. If water is coming through a crack under pressure, or the grade falls toward the house, or a downspout is discharging at the foundation, a drain is treating a symptom. We check those first because they are cheaper to fix and because a drain installed around an unaddressed cause will disappoint you.

South of the Missouri River you are working in loess over the Kansas City and Lansing Groups, alternating limestone beds separated by clay and shale. The Bethany Falls Limestone is the prominent ledge, 20 to 24 feet thick and quarried widely beneath the city. Where that rock is close to the surface, water perches on top of it and moves sideways.

Depth is not a spec here. It is a finding.

On the Kansas side the constraint is different. Sharpsburg and Grundy soils run 36 to 48 percent clay, and Grundy holds a saturated zone 0.3 to 1.0 meter deep during wet periods with a hydraulic conductivity as low as 0.1 micrometers per second. Water is not percolating down through that.

So we probe before we quote, rather than pricing a standard trench.

Most residential french drain runs price between quoted per linear foot from a written scope. Four things move a job within that band: total depth, whether we can reach a gravity outlet or need a pump, whether the trench crosses hardscape that has to be cut and restored, and access for equipment. A back yard reachable by a mini excavator prices very differently from one only reachable by hand through a 30-inch gate.

You get a written scope with the trench route, the depth, the outlet, the backfill spec and the restoration before anything is dug. We do not quote drainage off a photograph.

A drain with nowhere to send water is a buried holding tank. Every job needs a real outlet: daylight on a falling grade, a dry well sized for the volume, or a pumped discharge where neither is available. Establishing that is the first thing we do on site, because on a flat lot it can determine whether the project is worth doing at all.

Two local constraints shape this. In Kansas City, Ordinance 150452 prohibits tying drainage into the sanitary sewer. In Overland Park, OPMC 7.54.250 requires sump discharge stay five feet off any adjoining property line. Both rule out outlets a homeowner might otherwise assume were fine.